A wire-like structure called a wire harness, which is formed by bundling a plurality of wires such as electrical wires for electrically connecting electronic equipment, electronic components, and the like, is routed in a vehicle or a building structure. In recent years, from the viewpoint of improvement of space efficiency and the like, such a wire harness has come to be required to be as compact as possible without causing a decline in electric characteristics. In consequence, there is a need to calculate the outside diameter of the wire harness more accurately. Conventionally, however, that calculation is conventionally performed by experience or a method of calculation shown below, and particularly effective calculation method has not been proposed.
Referring to FIGS. 8A and 8B, a problem in the conventional method of calculating the outside diameter of a wire harness will be described. FIG. 8A shows a wire harness which is made up of a relatively small number of wires, and FIG. 8B shows a wire harness which is made up of a relatively large number of wires.
In the conventional method of calculation, as shown in FIG. 8A, when n wires a1 are given, the cross section of these wires a1, or a wire harness 10 consisting of these wires a1, is assumed to be circular. A diameter L of the wire harness 10 consisting of these wires a1 is determined on the basis of the formula:πL2/4=KΣ(πli2/4)
Here, li denotes the diameter of the wire a1, and K denotes a gap coefficient. Since it is difficult to determine respective gap coefficients in such a manner as to fit the number and layout of various wires, a fixed value is always used for all the cases irrespective of the number and layout of wires making up the wire harness 10.
However, as shown in FIGS. 8A and 8B, even in the case of the wire harnesses having equal diameters L, it is evident that areas of their gaps 11 and 11′ differ depending on the number and layout of the wires a1 and a′1 making up the respective wire harnesses. If that diameter L is nevertheless determined by always using the gap coefficient K of a fixed value in the above-described manner, that value becomes inaccurate, so that this method has been impractical.
Thus, there has been no practical method for determining the outside diameter of a wire harness which is made up of an arbitrary number of wires. It goes without saying that there has been no effective method of calculation for obtaining the outside diameter of the wire harness when the wires are bundled and packed into the smallest circular form possible.